title: [Anti-C1q antibodies in patients with systemic lupus erythematosus treated by rituximab].
abstract: OBJECTIVE
  To determine the time course of changes in the blood levels of antibodies (Ab) to complement component C1q (a-C1q) in patients with systemic lupus erythematosus (SLE) during rituximab (RTM) therapy and the association with organ injuries in SLE.
  
  
  METHODS
  The study involved 41 patients (3 men and 38 women; their median age was 27.5 (range 22-36) years) with definite SLE. Their blood a-C1q levels were determined by enzyme immunoassay. The levels and detection rates of a-C1q were estimated in relation to organ injuries, the time course of RTM therapy-induced changes in a-C1q levels were determined. High-positive (> 30 U/ml), low-positive (10-30 U/ml), and negative (< or = 10 U/ml) a-C1q levels were found.
  
  
  RESULTS
  A-C1q was detected in 19 (46.3%) patients with different clinical manifestations of SLE. The patients with renal diseases had high-positive levels of a-C1q statistically significantly more frequently than those without renal involvement (p = 0.04). Low-positive and negative a-C1q levels were found in 15 of 16 without nephritis. There was a statistically significant positive correlation of the concentration of a-C1q with Ab to double-stranded DNA (a-dsDNA), Ab to nucleosomes, the SLE Disease Activity Index 2000 (SLEDAI-2K), erythrocyturia, hematuria and a negative correlation between a-C1q and complement components C3 and C4. Just after one month of RTM therapy, the patients with nephritis were observed to have a statistically significant decrease in the levels of a-C1q (p = 0.002), which persisted 1 year after the treatment (p = 0.006). Nineteen patients with the higher baseline concentrations of a-C1q after RTM treatment showed a statistically significant decrease in the levels of a-C1q at 1-, 3-, 6-, and 12-month follow-up (p = 0.016, 0.02, 0.035, and 0.04, respectively) which was accompanied by the decreased SLEDAI-2K (p < 0.00004 at 1-, 3-, 6-, and 12-month follow-up).
  
  
  CONCLUSIONS
  The high levels of a-C1q were found statistically significantly more often in the patients with lupus nephritis than in those with SLE without renal involvement. The level of a-C1q statistically significantly reduced after RTM therapy and remained within the normal range during a year.
authors.forename: M E
authors.initials: ME
authors.lastname: Tsanyan
authors.forename: A V
authors.initials: AV
authors.lastname: Torgashina
authors.forename: E N
authors.initials: EN
authors.lastname: Aleksandrova
authors.forename: S K
authors.initials: SK
authors.lastname: Soloviev
authors.forename: E L
authors.initials: EL
authors.lastname: Nasonov
mesh_terms: D000328:Adult; D058846:Antibodies, Monoclonal, Murine-Derived / Q000627:therapeutic use*; D001323:Autoantibodies / Q000276:immunology; D015922:Complement C1q / Q000276:immunology*; D004247:DNA / Q000276:immunology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007124:Immunoenzyme Techniques; D007155:Immunologic Factors / Q000627:therapeutic use*; D008180:Lupus Erythematosus, Systemic / Q000188:drug therapy / Q000276:immunology* / Q000503:physiopathology; D008181:Lupus Nephritis / Q000188:drug therapy / Q000276:immunology; D008297:Male; D000069283:Rituximab; D012720:Severity of Illness Index; D013997:Time Factors; D055815:Young Adult
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D001323:Autoantibodies; D007155:Immunologic Factors; D000069283:Rituximab; D015922:Complement C1q; D004247:DNA